Evaluation of Weed Control Efficacy and Peanut Tolerance to Pyroxasulfone Herbicide in the South Texas Peanut Production Area

Aims: Determine weed efficacy and peanut tolerance to pyroxasulfone in the south Texas peanut growing area.

Study Design: Randomized complete block design with 3 replications.

Place and Duration of Study: Texas A&M AgriLife Research Site near Yoakum (29.276°N, 97.123°W) in south-central Texas during the 2013 and 2014 growing seasons.

Methodology: Two studies were conducted: 1) determine weed efficacy with pyroxasulfone and 2) determine variety tolerance to pyroxasulfone. Each plot at Yoakum consisted of two rows spaced 97 cm apart and 7.9 m long. Herbicides were applied with a CO2 compressed air backpack sprayer equipped with Teejet 11002 DG flat fan spray tips which delivered a spray volume of 190 L/ha at 180 kPa. In the weed efficacy study, all field plots were naturally infested with dense populations of Urochloa texana Buckl.(6 to 8 plants/m2) and Cucumis melo L. (6 to 8 plants/m2), and moderate Amaranthus palmeri S. Wats. (4 to 6 plants/m2) populations. In the variety tolerance study, pyroxasulfone alone at 0.12 and 0.25 kg ha-1 was compared with flumioxazin alone at 0.11 and 0.22 kg ha-1, flumioxazin plus pyroxasulfone at 0.07 + 0.09 and 0.14 + 0.18 kg ha-1, and S-metolachlor alone at 1.46 and 2.82 kg ha-1. All herbicides were applied preemergence and the test area was kept weed-free. Weed control and peanut injury was visually estimated on a scale of 0 to 100 (0 indicating no control or plant death and 100 indicating complete control or plant death), relative to the untreated control.

Results: Pyroxasulfone alone at 0.09 kg ha-1 provided erratic control of Urochloa texana and Cucumis melo but excellent control of Amaranthus palmeri. Peanut varieties exhibited excellent tolerance to pyroxasulfone at 0.12 and 0.25 kg ha-1.

Conclusion: These results indicate that pyroxasulfone can be an effective herbicide for weed control in south Texas peanut growing region. Also all peanut varieties showed excellent tolerance to pyroxasulfone.